The present invention relates to a fuel injection type gasoline engine, and more particularly to an air-to-fuel ratio (hereinafter referred to as A/F) control apparatus suitable for a gasoline engine for automobile.
The fuel injection type engine has considerably been used as gasoline engines for automobiles for its better controllability of A/F.
In the fuel injection type gasoline engine, a part of fuel injected from a fuel injection valve into an intake (suction) pipe adheres to the inner wall of the intake valve and/or an intake valve. In a steady state, the amount of adhered fuel is kept substantially constant. In a transient state such as an acceleration or deceleration condition, however, the amount of adhered fuel changes. Therefore, a method of merely controlling the amount of fuel to be supplied from the fuel injection valve cannot provide an accurate control of A/F in the transient state.
The conventional system, as has been disclosed in JP-B-62-341, employs a method in which in a transient driving state of engine such as an acceleration or deceleration condition, data of the supply amount of fuel is determined through an averaging operation processing and the amount of fuel to be actually supplied is corrected (increased or decreased) in accordance with a difference between the fuel supply amount data determined by the averaging operation processing and data of the fuel supply amount before the averaging operation processing. However, this conventional system has a problem that a compensation for A/F in the acceleration or deceleration condition is not sufficient since only the correction of increase or decrease based on the averaging operation processing of the fuel amount data immediately after the change to the transient driving state is made but any quantitative correction is not made.